An aqueous polymer dispersion whose polymer, present in disperse
distribution, is composed in free-radically polymerized form of
from 20 to 65% by weight of at least one vinylaromatic monomer (monomers
A),
from 30 to 75% by weight of at least one monomer having two conjugated,
ethylenically unsaturated double bonds (monomers B), and
from 0.5 to 10% by weight of at least one other monomer, C, selected from
the group consisting of .alpha.,.beta.-monoethyienically unsaturated mono-
and dicarboxylic acids and amide or ester derivatives thereof
and whose alkali metal ion content GA, based on the mass of the dispersed
polymer, is .gtoreq.0.5% by weight, the pH of the aqueous dispersion
medium being adjusted to a value below 6.
